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71.
72.
This article measures the degree to which academic economists have engaged in unethical behavior and the degree to which academic economists believe the profession as a whole engages in unethical behavior. Three main types of unethical behavior are examined: (1) falsification of research; (2) expropriation of graduate student research or including an undeserving co-author on a research paper; and (3) exchange of grades for gifts, money, or sex. Using a unique data set gathered at the 1998 American Economic Association (AEA) meetings, we find that there is a significant amount of misconduct, particularly in the second category.  相似文献   
73.
This paper provides a novel mechanism for identifying and estimating latent group structures in panel data using penalized techniques. We consider both linear and nonlinear models where the regression coefficients are heterogeneous across groups but homogeneous within a group and the group membership is unknown. Two approaches are considered—penalized profile likelihood (PPL) estimation for the general nonlinear models without endogenous regressors, and penalized GMM (PGMM) estimation for linear models with endogeneity. In both cases, we develop a new variant of Lasso called classifier‐Lasso (C‐Lasso) that serves to shrink individual coefficients to the unknown group‐specific coefficients. C‐Lasso achieves simultaneous classification and consistent estimation in a single step and the classification exhibits the desirable property of uniform consistency. For PPL estimation, C‐Lasso also achieves the oracle property so that group‐specific parameter estimators are asymptotically equivalent to infeasible estimators that use individual group identity information. For PGMM estimation, the oracle property of C‐Lasso is preserved in some special cases. Simulations demonstrate good finite‐sample performance of the approach in both classification and estimation. Empirical applications to both linear and nonlinear models are presented.  相似文献   
74.
Pseudo‐values have proven very useful in censored data analysis in complex settings such as multi‐state models. It was originally suggested by Andersen et al., Biometrika, 90, 2003, 335 who also suggested to estimate standard errors using classical generalized estimating equation results. These results were studied more formally in Graw et al., Lifetime Data Anal., 15, 2009, 241 that derived some key results based on a second‐order von Mises expansion. However, results concerning large sample properties of estimates based on regression models for pseudo‐values still seem unclear. In this paper, we study these large sample properties in the simple setting of survival probabilities and show that the estimating function can be written as a U‐statistic of second order giving rise to an additional term that does not vanish asymptotically. We further show that previously advocated standard error estimates will typically be too large, although in many practical applications the difference will be of minor importance. We show how to estimate correctly the variability of the estimator. This is further studied in some simulation studies.  相似文献   
75.
The nonparametric two-sample bootstrap is applied to computing uncertainties of measures in receiver operating characteristic (ROC) analysis on large datasets in areas such as biometrics, speaker recognition, etc. when the analytical method cannot be used. Its validation was studied by computing the standard errors of the area under ROC curve using the well-established analytical Mann–Whitney statistic method and also using the bootstrap. The analytical result is unique. The bootstrap results are expressed as a probability distribution due to its stochastic nature. The comparisons were carried out using relative errors and hypothesis testing. These match very well. This validation provides a sound foundation for such computations.  相似文献   
76.
Very little is known about the local power of second generation panel unit root tests that are robust to cross-section dependence. This article derives the local asymptotic power functions of the cross-section argumented Dickey–Fuller Cross-section Augmented Dickey-Fuller (CADF) and CIPS tests of Pesaran (2007), which are among the most popular tests around.  相似文献   
77.
One in five students report experimenting with tobacco before the age of 13 and most prevention efforts take place in the school setting. This study measures the effect of a single-lesson tobacco prevention curriculum, conducted by a health education center, focusing on knowledge of tobacco, ability to identify refusal techniques, and intent not to smoke. Data were collected, via electronic keypads, from students visiting a non-school, health education center in Michigan (n = 704 intervention and 85 comparison). Contingency table Chi-squared tests and t-tests demonstrated that a single lesson can improve general knowledge and ability to identify appropriate refusal techniques. Improvement in intent not to smoke was not significant because both groups had very high intent prior to implementation. Similar to results from other programs, multivariate logistic regression of gender, general knowledge, and skill identification revealed that only the skill variable was associated with intent not to smoke at pretest. Recommendations are given for further research and for designing more effective curricula or programs.  相似文献   
78.
Effective discharge planning is needed to facilitate clients' transition from psychiatric hospital wards to community care. Previous studies have shown that client outcomes can be improved by using a Transitional Discharge Model (TDM) that includes peer support and an extension of inpatient-practitioner relationships that are introduced prior to discharge. However, countries vary in many ways that may affect implementation of the model. This article describes some of the similarities and differences related to introducing transitional discharge in two countries: Canada and Scotland. It is important to elucidate facilitators and challenges in implementing the TDM to identify and disseminate strategies to aid implementation. Implications for future implementation of the model are also discussed.  相似文献   
79.
A laboratory experiment examined the effects of applying decision support system (DSS) technology to decision making in ill-structured problem environments under varying information conditions. Marketing executives participated in the experiment which investigated the effects of DSS availability, DSS training, and data availability on dependent variables that included: (1) the number of alternatives considered by a subject during decision making, (2) the period of time spent by a subject to complete the decision-making process, (3) the subject's perceived confidence in the decisions he or she had made, (4) the amount of data considered by a subject's during decision making, (5) the individual subject's decision processing, and (6) the subject's performance overall. Our results indicate that all three factors significantly affect the number of alternatives considered by subjects during the decision-making process. We therefore suggest that DSS training be coordinated with decision training in order to realize the potential of DSSs as described in the DSS literature.  相似文献   
80.
Martin E 《Demography》2007,44(2):427-440
This article draws on evidence from an exploratory survey of living situations to assess the validity of assumptions about residence and to offer methodological innovations to improve coverage of people with tenuous attachment to households. These innovations include more inclusive probes and questions used to compile the roster of household residents; a review of the places a person stayed the previous few months; and a Residential Attachment scale that measures strength of attachment to households. This scale shows that it takes more probing to list tenuously attached people than most surveys do, suggesting that tenuously attached people are likely to be omitted from the typical survey roster. The Residential Attachment scale is correlated with social and economic participation in households, suggesting that participation is fairly high even among those with tenuous or no residential attachment.  相似文献   
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